update testing related dependencies

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

vendor/github.com/nxadm/tail/tail_windows.go

@@ -0,0 +1,12 @@
+// +build windows
+
+package tail
+
+import (
+	"github.com/nxadm/tail/winfile"
+	"os"
+)
+
+func OpenFile(name string) (file *os.File, err error) {
+	return winfile.OpenFile(name, os.O_RDONLY, 0)
+}